1. Field of the Invention
The invention relates in general to an image editing method, and more particularly to a method for converting an original image to a simulated image satisfying a lens optical characteristic through distances between objects in the original image and a capturing lens.
2. Description of the Related Art
As image capturing techniques rapidly develop, digital cameras are now indispensible electronic apparatuses in modern daily life. To handily operate a digital camera, a common consumer camera (e.g., a point-and-shoot camera or a camera equipped in a cell phone) is provided with a greater field of depth for easily capturing clear images.
A professional camera (e.g., single-lens reflex (SLR) camera), featuring a large aperture and a small field of depth, is preferably operated by a user with good photographing skills. Images captured by an SLR camera show better layering effects and thus more professional photographing results, which cannot be rendered by a common consumer camera.
To simulate a photographing result of another type of camera, certain consumer cameras, cell phones or computers carry an image processing module for simulating a photographing result of another type of camera. In other words, a photographing result of a professional camera can be achieved by an image captured by a consumer camera through image processing. For example, the image processing module is implemented by a hardware circuit or software.
In principle, in a conventional image processing method, a focal object in an image is selected, and a blur process is performed on parts of the image except the focal object. FIGS. 1A to 1C show schematic diagrams of a conventional image simulating method. For example, an image captured by a consumer camera is as shown in FIG. 1A. In contribution to a greater field of depth of a consumer camera, various objects in the image are clearly presented.
To further process the image, the user may select any object in the image as a focal object. Referring to FIG. 1B, the user may select an automobile as a focal object using a selection frame 10. The focal object in the selection frame 10 is kept clear while parts outside (dotted regions) the selection frame 10 undergo a blur process. After processing the image, the focal object appears clear whereas other parts except the focal object appear more blurry, thus rendering layering effects similar to those provided by a professional camera.
Similarly, referring to FIG. 1C, after selecting flowers in the image as a focal object, the image processing module keeps the focal object in the selection frame 10 clear and performs a blur process on the parts outside (dotted regions) the selection frame. After processing the image, the focal object appears clear whereas other parts except the focal object appear more blurry, thus rendering layering effects similar to those provided by a professional camera.
A conventional image processing module generally performs a blur process using information of an original image. In other words, a conventional image processing module, regarding the selection frame 10 (the focal object) as a center, processes objects farther away from the selection frame 10 with higher blur levels and processes objects closer to the selection frame 10 with lower blur levels. Taking FIG. 1B for example, regions with a higher density of the dotted lines appear more blurry than regions with a lower density of the dotted lines. That is to say, in FIG. 1B, peripheral areas of the rectangular image are located farthest away from the selection frame 10 and hence have more blurry images. Taking FIG. 10 for example, an upper-left corner of the rectangular image is farthest away from the selection frame 10 and thus has the more blurry images.
Although with the above image processing, an image obtained by the conventional image processing through simulating a professional camera is nevertheless noticeably different from an image actually captured by a professional camera—information obtained after performing a blur process on a captured image in fact does not match an actual condition. Therefore, there is a need for an image processing method for more realistically simulating a photographing result of another camera.